Optical touch system

ABSTRACT

An image system comprises a light source, an image sensing device, and a computing apparatus. The light source is configured to illuminate an object comprising at least one portion. The image sensing device is configured to generate a picture comprising an image. The image is produced by the object and comprises at least one part corresponding to the at least one portion of the object. The computing apparatus is configured to determine an intensity value representing the at least one part and to determine at least one distance between the at least one portion and the image sensing device using the intensity value and a dimension of the at least one part of the image.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on, and claims priority from, TaiwanPatent Application Serial Number 100135998, filed on Oct. 5, 2011, thedisclosure of which is hereby incorporated by reference herein in itsentirety.

BACKGROUND

1. Technical Field

The present invention relates to an image system.

2. Related Art

A time-of-flight camera (TOF camera) is a camera system that createsdistance data with the time-of-flight (TOF) principle. The simplestversion of a time-of-flight camera uses light pulses. The illuminationis switched on for a very short time, and the generated light pulseilluminates the scene and is reflected by the objects. The camera lensgathers the reflected light, forming images onto the sensor plane.Depending on the distances, the incoming light may experience a delay.The camera has photo diodes (PDs), which convert incoming light intocurrents. In analog timing imagers, connected to the photo diode arefast switches, which direct the current to one of plural memory elements(e.g. a capacitor). In digital timing imagers, a time counter, runningat several gigahertz, is connected to each photo detector and stopscounting when light is sensed.

In an analog timer, a PD pixel uses two switches and two memoryelements. The switches are controlled by a pulse with the same length asthe light pulse, where the control signal of one switch is delayed byexactly the pulse width. Depending on the delay, different amounts ofelectrical charge are respectively stored in the two memory elements.The distance from the camera to the object can be estimated by comparingthe amounts of electrical charge stored in the two memory elements.

Light generated for being sensed by TOF cameras illuminates the completescene. Light may go through different paths before it arrives at theobject, causing the estimated distance to be greater than the actualdistance.

SUMMARY

One embodiment of the present invention provides an image system, whichcomprises a light source, an image sensing device, and a computingapparatus. The light source is configured to illuminate an objectcomprising at least one portion. The image sensing device is configuredto generate a picture. The picture comprises an image produced by theobject. The image comprises at least one part corresponding to the atleast one portion of the object. The computing apparatus is configuredto determine an intensity value representing the at least one part ofthe image and to determine at least one distance between the at leastone portion of the object and the image sensing device using theintensity value and a dimension of the at least one part of the image.

Another embodiment of the present invention provides an image system,which comprises a light source, an image sensing device, and a computingapparatus. The light source is configured to illuminate an object. Theobject comprises a first portion and a second portion connected with thefirst portion. The first portion comprises reflectance different fromthat of the second portion. The image sensing device is configured togenerate a picture comprising an image produced by the object. The imagecomprises a first part corresponding to the first portion of the objectand a second part corresponding to the second portion of the object. Thecomputing apparatus is configured to determine the reflectance of thesecond portion of the object using an intensity value representing thefirst part of the image and an intensity value representing the secondpart of the image.

Another embodiment of the present invention provides an image system,which comprises a light source, an image sensing device, and a computingapparatus. The light source is configured to illuminate an object. Theimage sensing device is configured to generate, in sequence, a firstpicture and a second picture. The first and second pictures respectivelycomprise an image produced by the object. The computing apparatus isconfigured to determine a distance between the object and the imagesensing device by the image of the first picture. The computingapparatus is further configured to determine a first intensity valuerepresenting the image of the first picture and a second intensity valuerepresenting the image of the second picture and corresponding to thefirst intensity value. Moreover, the computing apparatus is configuredto determine a travel distance of the object from the time that thefirst picture is generated until the time that the second picture isgenerated using the first intensity value, the second intensity value,and the distance.

Another embodiment of the present invention provides an image system,which comprises a light source, an image sensing device, and a computingapparatus. The light source is configured to illuminate an objectcomprising a plurality of portions. The image sensing device isconfigured to generate a plurality of pictures. Each picture comprisesan image produced by the object. Each image comprises a plurality ofparts corresponding to the plurality of portions of the object. Thecomputing apparatus is configured to generate motion signalscorresponding to the plurality of portions of the object according tochanges in positions and intensity values of the plurality of parts ofthe images.

To provide a better understanding of the above-described objectives,characteristics and advantages of the present invention, a detailedexplanation is provided in the following embodiments with reference tothe drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described according to the appended drawings inwhich:

FIG. 1 is a schematic illustration depicting an image system configuredto take an image of an object according to one embodiment of the presentinvention;

FIG. 2 is a schematic illustration of a picture according to oneembodiment of the present invention;

FIG. 3 schematically demonstrates distances between the portions of anobject and an image sensing device according to one embodiment of thepresent invention;

FIG. 4 schematically demonstrates a three-dimensional image according toone embodiment of the present invention;

FIG. 5 is a schematic illustration depicting an image system and anobject according to another embodiment of the present invention;

FIG. 6 is a schematic illustration of a picture according to anotherembodiment of the present invention;

FIG. 7 is a timing diagram demonstrating the operations of a lightsource and an image sensing device according to one embodiment of thepresent invention;

FIG. 8 schematically illustrates a visible light picture according toone embodiment of the present invention;

FIG. 9 is a block diagram illustrating a computing apparatus accordingto one embodiment of the present invention;

FIG. 10 is a block diagram illustrating a portion of functions of animage system according to one embodiment of the present invention;

FIG. 11 is a flow diagram demonstrating the steps of a method ofdetecting a gesture according to one embodiment of the presentinvention; and

FIG. 12 is a block diagram illustrating an automatic exposure controldevice according to one embodiment of the present invention.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

The following description is presented to enable any person skilled inthe art to make and use the disclosed embodiments, and is provided inthe context of a particular application and its requirements. Variousmodifications to the disclosed embodiments will be readily apparent tothose skilled in the art, and the general principles defined herein maybe applied to other embodiments and applications without departing fromthe spirit and scope of the disclosed embodiments. Thus, the disclosedembodiments are not limited to the embodiments shown, but are to beaccorded the widest scope consistent with the principles and featuresdisclosed herein.

The image system of some embodiments of the present invention may detectthe intensity value of a portion of an object, calculate a distancebetween the portion of an object and an image sensing device of theimage system, and calculate another distance between another portion ofthe object and the image sensing device, the reflectance of the anotherportion, the relative positions of the two portions using the intensityvalue and the distance, or the distance that the object moves in a timeinterval. In some embodiments, the distance between a portion of theobject and the image sensing device can be the distance measured fromthe portion of the object to the image sensing device of the imagesystem. In some embodiments, the distance between a portion of theobject and the image sensing device can be the distance measured fromany location adjacent to the portion of the object to the image sensingdevice.

FIG. 1 is a schematic illustration depicting an image system configuredto take an image of an object 2 according to one embodiment of thepresent invention. FIG. 2 is a schematic illustration of a pictureaccording to one embodiment of the present invention. Referring to FIGS.1 and 2, the image system 1 comprises a light source 11, an imagesensing device 12, and a computing apparatus 13. The light source 11 isconfigured to illuminate an object 2 that may comprise a plurality ofportions (21, 22, 23 and 24). The image sensing device 12 may generate apicture 3 as shown in FIG. 2. The picture 3 may comprise an image 31created by the object 2 under illumination by electromagnetic radiation.The image 31 may comprise a plurality of parts (311, 312, 313, and 314)corresponding to the plurality of portions (21, 22, 23 and 24). Thecomputing apparatus 13 is configured to determine the intensity valuesrepresenting the plurality of parts (311, 312, 313, and 314),respectively. The computing apparatus 13 can be further configured todetermine distances between the plurality of portions (21, 22, 23 and24) and the image sensing device 12 using a dimension of one of theplurality of parts (311, 312, 313, and 314) and the intensity values.With the distance values, a three-dimensional image of the object 2 canbe constructed.

When light from the light source 11 emits on the object 2, the object 2reflects the light, and the image sensing device 12 receives a portionof the reflected light. Due to different distances from the imagesensing device 12, the image 31 of the object 2 exhibit significantlyvaried intensity distributions. In addition, the object 2 may comprise aplurality of portions having different reflectance. The portion with ahigher reflectance reflects more light, creating a brighter part in theimage, while the portion with a lower reflectance reflects less light,creating a darker part in the image.

In some embodiments, the object 2 may be any substance in the realworld. In some embodiments, the object 2 can be, but is not limited to,a human being. As shown in FIG. 3, when the object 2 is a human being,the object 2 may comprise a plurality of portions (21, 22, 23, and 24),such as a face portion 21, a hand portion 22, another hand portion 23and a body portion 24. Each portion is differently distanced from theimage sensing device 12. The face portion 21 corresponds to the facepart 311 of the image 31; the hand portion 22 corresponds to the handpart 312 of the image 31; the hand portion 23 corresponds to the handpart 313 of the image 31; and the body portion 24 corresponds to thebody part 314 of the image 31.

Normally, a specified physical quantity or intensity is inverselyproportional to the square of the distance from the source of thatphysical quantity (i.e., inverse-square law). Accordingly, the relativepositions of the face portion 21, the hand portion 22, and the handportion 23 can be determined by the intensity values respectivelyrepresenting the face part 311, the hand part 312, and the hand part313. After the computing apparatus 13 analyzes the picture 3, it can befound that the intensity value representing the hand part 312 is higherthan the intensity value representing the face part 311, and theintensity value representing the face part 311 is higher than theintensity value representing the hand part 313. With the analyzedresult, the computing apparatus 13 can determine either of thefollowing: the hand portion 22 of the object 2 is closer to the imagesensing device 12 than the face portion 21; or the hand portion 22 ofthe object 2 is in front of the face portion 21, and that the handportion 23 of the object 2 is farther away from the image sensing device12 than the face portion 21; or the hand portion 23 of the object 2 isbehind the face portion 21.

In some embodiments, the intensity value representing the face part 311,the hand part 312 or the hand part 313 of the image 31 can be an averageof the intensities of all pixels of the face part 311, the hand part 312or the hand part 313. In some embodiments, the intensity valuerepresenting the face part 311, the hand part 312 or the hand part 313of the image 31 can be an average of the intensities of a portion ofpixels of the face part 311, the hand part 312 or the hand part 313.

Moreover, the distances between the portions of the object 2 havingdifferent intensity values and the image sensing device 12 can befurther determined by the intensity distribution and the theory on thinlenses.

As shown in FIGS. 2 and 3, the computing apparatus 13 can determine theintensity value I₁ of the face part 311 of the image 31, the intensityvalue I₂ of the hand part 312 of the image 31, and the intensity valueI₃ of the hand part 313 of the image 31. The computing apparatus 13 canfurther determine a dimension d₁ of the face part 311 of the image 31.With the help of the theory on thin lenses, the computing apparatus 13can determine the distance l₁ between the face portion 21 and the imagesensing device 12 with the dimension d₁ of the face part 311, where thefocus length of the image sensing device 12 and the actual size of theface portion 12 are known. The dimension d₁ used for determining thedistance l₁ between the face portion 21 and the image sensing device 12is not limited to the width of the face portion 21. The length of theface portion 21 or the like can be a choice. The distance l₂ between theimage sensing device 12 and the hand portion 22 and the distance l₃between the image sensing device 12 and the hand portion 23 can bedetermined with the following equations (1) and (2).

$\begin{matrix}{l_{2} = {l_{1} \times \sqrt{\frac{I_{1}}{I_{2}}}}} & (1) \\{l_{3} = {l_{1} \times \sqrt{\frac{I_{1}}{I_{3\;}}}}} & (2)\end{matrix}$

The distances between the image sensing device 12 and other portions ofthe object 2, such as foot portions, can be determined using suchmethod. The computing apparatus 13 may construct a three-dimensionalimage, as shown in FIG. 4, using the distances between each portion ofthe object 2 and the image sensing device 12 and the image 31 of thepicture 3.

In the above embodiments, skin reflects light in the face portion 21,the hand portion 22, and the hand portion 23 of the object 2. Therefore,these portions (21, 22, and 23) have similar reflectance so that whendetermining distances, the effect of reflectance can be ignored. Theobject 2 may include other portions, for example, a body portion wearingclothes, having reflectance different from that of skin. When using aportion, such as the face portion 21 of the object 2, to determine thedistance between the body portion 24 and the image sensing device 12,the difference between the reflectance of the body portion 24 and theface portion 21 needs to be considered.

If the skin has a reflectance of A, the intensity value I₄ representsthe body part 314 of the image 31, and if the body portion 24 has areflectance of A′, the distance l₄ between the body portion 24 and theimage sensing device 12 can be calculated using the following equation(3).

$\begin{matrix}{l_{4} = {l_{1} \times \sqrt{\frac{I_{1} \times A^{\prime}}{{I_{4} \times A}\;}}}} & (3)\end{matrix}$

In some embodiments, a portion of the object 2 can also be calculated.For example, the face portion 21 and the body portion 24 of the object 2are connected, and if the face portion 21 and the body portion 24 of theobject 2 stay straight, the two portions (21 and 24) have substantiallythe same distance to the image sensing device 12. If the body part 314of the image 31 has a reflectance of I₄ and the face part 311 has areflectance of I₁, the reflectance A′ of the body portion 24 can bedetermined by the following equation (4).

$\begin{matrix}{A^{\prime} = {\frac{I_{4}}{I_{1}} \times A}} & (4)\end{matrix}$

In some embodiments, a travel distance of an object can be determinedaccording to the intensity values of two pictures. With the face portion21 of the object 2 as an example, referring to FIGS. 2, 3, 5 and 6, whenthe face portion 21 of the object 2 is distant by l₁ from the imagesensing device 12, the image sensing device 12 generates a picture 3,and the intensity value I₁ representing the face part 311 can bedetermined from the image 31 of the picture 3. As mentioned above, thedistance l₁ between the face portion 21 of the object 2 and the imagesensing device 12 can be estimated using a dimension d1 of the face part311.

After the object 2 moves to a location where its face portion 21 isdistant by l₅ from the image sensing device 12, the image sensing device12 generates a picture 4. The intensity value I₅ representing the facepart 311 of the image 41 of the picture 4 can then be obtained. Thedistance l₅ can be determined using the distance l₁, the intensity valueI₁, and the intensity value I₅.

In some embodiments, a dimension d₂ of the image 41 can be obtained.Similarly, with the help of the theory on thin lenses, the distance l₅can be calculated using the dimension d₂. In some embodiments, when thedistance l₅ determined by the theory on thin lenses is different fromthe distance l₅ determined by the inverse-square law, the two distancesl₅ are averaged or averaged by weighted to obtain a calibrationdistance. In some embodiments, the distance 1₅ determined by the theoryon thin lenses can be used as a basis to correct the reflectance of thecorresponding portion of the object 2 such that the distance determinedby the inverse-square law and intensity values can be similar to thedistance determined by the theory on thin lenses.

In some embodiments, referring to FIGS. 2, 3, 5, and 6, the imagesensing device 12 may generate a plurality of pictures 3 and 6. Eachpicture 3 or 6 may comprise an image 31 or 41 produced by the object 2.Each image 31 or 41 may comprise a plurality of parts (311, 312, 313,and 314) corresponding to the plurality of portions (21, 22, 23, and 24)of the object 2. The computing apparatus 13 is configured to compare thepositions of the plurality of parts (311, 312, 313, and 314) of theimages 31 with the positions of the plurality of parts (311, 312, 313,and 314) of the images 41 to determine the change of the position of theobject 2 in a transverse direction relative to the image sensing device12. Furthermore, the computing apparatus 13 can determine the traveldistance of each portion (21, 22, 23, or 24) of the object 2 caused bythe movement of the portion (21, 22, 23, or 24) toward or away from theimage sensing device 12 using the intensity values respectivelyrepresenting the parts (311, 312, 313, and 314) of the images 31 and 41.The computing apparatus 13 can further determine the relativethree-dimensional motion of each portion (21, 22, 23, or 24) of theobject 2 and thereby generate corresponding motion signals.

Referring to FIG. 7, the object 2 may reflect light that does not comefrom the light source 11, accordingly change the intensities of theimage 31 of the picture 3, thereby causing a distance calculation error.In some embodiments, during the period 71 the light source is turned on,the image sensing device 12 is activated for an image-capturing period72 to generate a picture taken with a flash; and when the light sourceis turned off, the image sensing device 12 is activated for anotherimage-capturing period 73 to generate a picture taken without a flash.The picture 3 can be obtained is by subtracting the picture takenwithout a flash from the picture taken with a flash. As a result, theerror caused by the light that does not come from the light source canbe reduced.

Referring to FIG. 10, in some embodiments, the image system 1 maycomprise a micro-controller 101, a DC/DC converter 103, a pixel array102, and a light source 11. The DC/DC converter 103 is coupled with thelight source 11 for providing electricity. The micro-controller 101 iscoupled with the DC/DC converter 103 and the pixel array 102 forcontrolling the electricity supply and the capturing of images. Themicro-controller 101 can be programmed to control the pixel array 102 togenerate a picture taken with a flash when the light source 11 is turnedon, and to generate a picture taken without a flash when the lightsource 11 is turned off.

In some embodiments, the activation time of the light source 11 of theimage system 1 is adjustable such that the intensity value of at leastone portion of the image 31 is in a predetermined range. Referring toFIG. 2, in some embodiments, the image system 1 can adjust theactivation time of the light source 11 so that the intensity valuerepresenting the face part 311 of the image 31 can fall within apredetermined intensity range, while the present invention is notlimited to such embodiments. After the image 31 is captured, the facepart 311 of the image 31 is identified. The present image identificationtechnologies can be applied to identify the face part 311 of the image31. After the face part 311 of the image 31 is identified, an intensityvalue representing the face part 311 of the image 31 can be calculated.The intensity value can be an average of the intensities of the pixelsof the face part 311, an average of the intensities of a portion ofpixels of the face part 311, or an intensity value sufficientlyrepresenting the face part 311. Thereafter, the intensity valuerepresenting the face part 311 is compared with a predeterminedintensity range. If the intensity value representing the face part 311is not within the predetermined intensity range, the activation time ofthe light source 11 is decreased or increased to adjust the intensityvalue representing the face part 311 to be within the predeterminedintensity range.

In some embodiments, the exposure time of the image sensing device 12 ofthe image system 1 is adjustable such that the intensity value of atleast one portion of the image 31 can be within a predeterminedintensity range. In some embodiments, the image system 1 adjusts theexposure time of the image sensing device 12 so that the face part 311of the image 31 falls within a predetermined intensity range; however,the present invention is not limited to such embodiments. In someembodiments, after the face part 311 of the image 31 is identified, theintensity value representing the face part 311 of the image 31 can becalculated. Thereafter, the intensity value representing the face part311 is compared with a predetermined intensity range. If the intensityvalue representing the face part 311 is not within the predeterminedintensity range, the exposure time of the image sensing device 12 isdecreased or increased to adjust the intensity value representing theface part 311 to be within the predetermined intensity range.

In some embodiments, the light source 11 is configured to emit invisiblelight, and the image sensing device 12 is configured to be sensitive tothe invisible light. The face part 311 of the image 31 can be directlyidentified from the picture 3 generated by the image sensing device 12.

Referring to FIGS. 2 and 8, in some embodiments, the light source 11generates invisible light, and the image sensing device 12 is configuredto detect the invisible light. The image system 1 may further compriseanother image sensing device 14, which is configured to detect visiblelight. The image sensing device 14 can generate a visible light picture8 as shown in FIG. 8. The visible light picture 8 may comprise an image81. The visible light picture 8 can be used for identification of theface part of the image 81 and for determination of the location of theface part. Afterward, at the same location, intensity values aredetermined from a picture taken with a flash and a picture taken withouta flash, respectively. The difference between the intensity values iscompared with a predetermined intensity range for adjusting exposuretime. Subsequently, the distances between other portions of the objectand the image sensing device 12 are determined by the size of the facepart and the intensity value representing the face part.

In some embodiments, as shown in FIG. 8, when the object 2 is a humanbeing, the location of his face is detected preferably using the imageof a visible light picture 8. The image system 1 first generates avisible light picture 8, then, the location of the human face isidentified and/or a dimension representing the human face is determined.Thereafter, invisible light is generated and an invisible light pictureis obtained. Finally, the gesture or movement of the object isdetermined using the invisible light picture.

In some embodiments, the light source 11 emits infrared light, and theimage sensing device 12 is configured to correspondingly detect infraredlight.

In some embodiments, the image sensing device 12 or 14 comprises aglobal shutter image sensor.

The image sensing device 12 or 14 may comprise an automatic exposurecontrol device. In some embodiments, as shown in FIG. 12, the imagesensing device 12 or 14 may comprise a pixel array 102, an automaticexposure control device 121, and an exposure/gain register 122. Thepixel array 102 receives light to generate a picture. The automaticexposure control device 121 is coupled with the pixel array 102 toreceive the picture generated by the pixel array 102. The automaticexposure control device 121 can compare a portion of the image of thepicture and a predetermined intensity range, and determine anexposure/gain value. The exposure/gain register 122 is coupled with thepixel array 102 and the automatic exposure control device 121 and canstore the exposure/gain value, which is used to control the exposuretime of the pixel array 102. The above embodiment is an example, whichshould not be used to limit the present invention.

As shown in FIG. 9, in some embodiments, the computing apparatus 13 maycomprise a processor 91, a memory device 92, and an input/output device93. The memory device 92 can store the programs for operating thecomputing apparatus 13, the programs for performing the methods of theembodiments of the present disclosure, and the data required forperforming the afore-mentioned programs. The processor 91 is configuredto execute programs. The input/output device 93 can couple with anexternal device such as a communication device and an image sensingdevice.

One embodiment of the present invention discloses a method of detectinga gesture. Referring to FIG. 11, in Step S1101, a picture is obtained,which comprises an image of a human being. The picture can be generatedby an image sensing device for detecting visible light or an imagesensing device for detecting invisible light. In Step S1102, the humanface of the picture is identified and the location of the human face isdetermined. The picture used to identify the human face can be a visiblelight picture or an invisible light picture. In Step S1103, a picturetaken with a flash and a picture taken without a flash are obtained. InStep S1104, a difference value is determined between the intensity valuerepresenting, the human face of the picture taken with a flash and theintensity value representing the human face of the picture taken withouta flash. In Step S1105, the difference value is compared with apredetermined intensity range. If the difference value is not in thepredetermined intensity range, the activation time of the light sourceor the exposure time of the image sensing device is adjusted. In StepS1106, a new picture is generated. In Step S1107, the reflectance of thehuman face and the body portion is determined and stored. The distancebetween the human face and the image sensing device can be determinedusing a dimension of the human face of the image. The reflectance of thebody portion can be determined using the intensity values representingthe human face and the body portion. In Step S1108, distances betweenother portions of the object and the image sensing device can bedetermined using the distance between the human face of the object andthe image sensing device, the intensity value representing the humanface of the image, and the intensity values representing other portionsof the image of the human being. A three-dimensional human image can beconstructed using the above distances and the gesture of the object canbe determined accordingly. In some embodiments, the movement or thegesture of the object can be determined using a newly captured picture,the distance between the human face and the image sensing device, andthe intensity value representing the human face of the image.

In some embodiments, the system may store a predetermined human facereflectance. The inaccuracy between the calculated distances from thehuman face to the image sensing device can be applied to modify thestored predetermined human face reflectance to obtain a new human facereflectance, which is then stored back to the system.

It will be apparent to those skilled in the art that variousmodifications can be made to the disclosed embodiments. It is intendedthat the specification and examples be considered as exemplary only,with the true scope of the disclosure being indicated by the followingclaims and their equivalents.

What is claimed is:
 1. An image system comprising: a light sourceconfigured to illuminate an object comprising at least one portion; animage sensing device configured to generate a picture comprising animage produced by the object, wherein the image comprises at least onepart corresponding to the at least one portion of the object; and acomputing apparatus configured to determine an intensity valuerepresenting the at least one part of the image and to determine atleast one distance between the at least one portion of the object andthe image sensing device using the intensity value and a dimension ofthe at least one part of the image, wherein the picture is obtained bysubtracting a picture that is taken when the light source is turned offfrom a picture that is taken when the light source is turned on.
 2. Theimage system of claim 1, wherein the object comprises a plurality ofportions, and the computing apparatus determines a plurality of firstdistances corresponding to the plurality of portions and athree-dimensional image using the plurality of first distances and thepicture.
 3. The image system of claim 1, wherein the light source emitsinvisible light and the image sensing device is configured to detect theinvisible light.
 4. The image system of claim 3, wherein the lightsource emits infrared light and the image sensing device is configuredto detect infrared light.
 5. The image system of claim 3, furthercomprising a visible light image sensing device configured to generate avisible light picture comprising an image of the object, wherein thecomputing apparatus determines a position of the at least one part ofthe image of the picture and the dimension using the visible lightpicture.
 6. The image system of claim 1, wherein the image sensingdevice is a global shutter image sensor.
 7. The image system of claim 1,wherein the computing apparatus compares the intensity valuerepresenting the at least one part of the image with a predeterminedintensity range to determine either the time during which the lightsource is turned on or the exposure time of the image sensing device. 8.An image system comprising: a light source configured to illuminate anobject comprising at least one portion; an image sensing deviceconfigured to generate a picture comprising an image produced by theobject, wherein the image comprises at least one part corresponding tothe at least one portion of the object; and a computing apparatusconfigured to determine an intensity value representing the at least onepart of the image and to determine at least one distance between the atleast one portion of the object and the image sensing device using theintensity value and a dimension of the at least one part of the image,wherein the image sensing device is a global shutter image sensor,wherein the image sensing device comprises a pixel array and anautomatic exposure control device coupled with the pixel array, andwherein the automatic exposure control device is configured to comparethe intensity value representing the at least one part of the image witha predetermined intensity range to determine an exposure control value,which is used to determine exposure time of the pixel array.
 9. An imagesystem comprising: a light source configured to illuminate an objectcomprising at least one portion; an image sensing device configured togenerate a picture comprising an image produced by the object, whereinthe image comprises at least one part corresponding to the at least oneportion of the object; and a computing apparatus configured to determinean intensity value representing the at least one part of the image andto determine at least one distance between the at least one portion ofthe object and the image sensing device using the intensity value and adimension of the at least one part of the image, wherein the objectcomprises two connected portions and the image comprises two connectedparts corresponding to the two connected portions, and wherein thecomputing apparatus determines intensity values respectivelyrepresenting the two connected parts and a second distance between oneof the two connected portions and the image sensing device, andreflectance of another of the two connected portions, according to theintensity values respectively representing the two connected parts andthe second distance.
 10. An image system comprising: a light sourceconfigured to illuminate an object comprising at least one portion; animage sensing device configured to generate a picture comprising animage produced by the object, wherein the image comprises at least onepart corresponding to the at least one portion of the object; and acomputing apparatus configured to determine an intensity valuerepresenting the at least one part of the image and to determine atleast one distance between the at least one portion of the object andthe image sensing device using the intensity value and a dimension ofthe at least one part of the image, wherein the computing apparatusdetermines two third distances between two portions of the objectrespectively corresponding to two parts of the image and the imagesensing device by dimensions of the two parts of the image, and checksone of the two third distances with another of the two third distances.11. An image system comprising: a light source configured to illuminatean object comprising at least one portion; an image sensing deviceconfigured to generate a picture comprising an image produced by theobject, wherein the image comprises at least one part corresponding tothe at least one portion of the object; and a computing apparatusconfigured to determine an intensity value representing the at least onepart of the image and to determine at least one distance between the atleast one portion of the object and the image sensing device using theintensity value and a dimension of the at least one part of the image,wherein the computing apparatus determines two fourth distances betweentwo portions of the object respectively corresponding to two parts ofthe image and the image sensing device by dimensions of the two parts ofthe image, and checks reflectance of one of the two portions with thetwo fourth distances.
 12. An image system comprising: a light sourceconfigured to illuminate an object comprising a first portion and asecond portion connected with the first portion, wherein the firstportion comprises reflectance different from that of the second portion;an image sensing device configured to generate a picture comprising animage produced by the object, the image comprising a first partcorresponding to the first portion of the object and a second partcorresponding to the second portion of the object; and a computingapparatus configured to determine reflectance of the second portion ofthe object using an intensity value representing the first part of theimage and an intensity value representing the second part of the image,wherein the computer apparatus compares the intensity value representingthe first part of the image with a predetermined intensity range todetermine either the time during which the light source is turned on orthe exposure time of the image sensing device.
 13. The image system ofclaim 12, wherein the computing apparatus determines a dimension of thefirst part of the image and a distance between the first portion of theobject and the image sensing device by the dimension.
 14. The imagesystem of claim 12, wherein the light source emits invisible light andthe image sensing device detects the invisible light, and the imagesystem further comprises a visible light image sensing device thatdetermines a position of the first part of the image and a dimension ofthe first part of the image.
 15. The image system of claim 14, whereinthe light source emits infrared light and the image sensing devicedetects infrared light.
 16. The image system of claim 12, wherein theimage sensing device detects visible light.
 17. The image system ofclaim 12, wherein the image sensing device is a global shutter imagesensor.
 18. An image system comprising: a light source configured toilluminate an object comprising a first portion and a second portionconnected with the first portion, wherein the first portion comprisesreflectance different from that of the second portion; an image sensingdevice configured to generate a picture comprising an image produced bythe object, the image comprising a first part corresponding to the firstportion of the object and a second part corresponding to the secondportion of the object; and a computing apparatus configured to determinereflectance of the second portion of the object using an intensity valuerepresenting the first part of the image and an intensity valuerepresenting the second part of the image, wherein the picture isobtained by subtracting a picture that is taken when the light source isturned off from a picture that is taken when the light source is turnedon.
 19. An image system comprising: a light source configured toilluminate an object comprising a first portion and a second portionconnected with the first portion, wherein the first portion comprisesreflectance different from that of the second portion; an image sensingdevice configured to generate a picture comprising an image produced bythe object, the image comprising a first part corresponding to the firstportion of the object and a second part corresponding to the secondportion of the object; and a computing apparatus configured to determinereflectance of the second portion of the object using an intensity valuerepresenting the first part of the image and an intensity valuerepresenting the second part of the image, wherein the image sensingdevice is a global shutter image sensor, and wherein the image sensingdevice comprises a pixel array and an automatic exposure control devicecoupled with the pixel array, wherein the automatic exposure controldevice compares the intensity value representing the first part of theimage with a predetermined intensity range to determine an exposurecontrol value, which is used to control exposure time of the pixelarray.
 20. An image system comprising: a light source configured toilluminate an object; an image sensing device configured to generate, insequence, a first picture and a second picture respectively comprisingan image produced by the object; a computing apparatus configured todetermine a distance between the object and the image sensing device bythe image of the first picture, to determine a first intensity valuerepresenting the image of the first picture and a second intensity valuerepresenting the image of the second picture and corresponding to thefirst intensity value, and to determine a travel distance of the objectfrom the time that the first picture is generated until the time thatthe second picture is generated using the first intensity value, thesecond intensity value, and the distance; and a visible light imagesensing device configured to generate a visible light picture comprisingan image of the object, wherein the computing apparatus determines aposition and a dimension of a part of the image of the first or secondpicture, and wherein the light source emits invisible light and theimage sensing device detects the invisible light.
 21. The image systemof claim 20, wherein the image sensing device detects visible light. 22.The image system of claim 20, wherein the image sensing device is aglobal shutter image sensor.
 23. An image system comprising: a lightsource configured to illuminate an object; an image sensing deviceconfigured to generate, in sequence, a first picture and a secondpicture respectively comprising an image produced by the object; acomputing apparatus configured to determine a distance between theobject and the image sensing device by the image of the first picture,to determine a first intensity value representing the image of the firstpicture and a second intensity value representing the image of thesecond picture and corresponding to the first intensity value, and todetermine a travel distance of the object from the time that the firstpicture is generated until the time that the second picture is generatedusing the first intensity value, the second intensity value, and thedistance, wherein the image sensing device is a global shutter imagesensor, wherein image sensing device comprises a pixel array and anautomatic exposure control device coupled with the pixel array, andwherein the automatic exposure control device compares the firstintensity value with a predetermined intensity range to determine anexposure control value, which is used to determine exposure time of thepixel array.
 24. An image system comprising: a light source configuredto illuminate an object comprising a plurality of portions; an imagesensing device configured to generate a plurality of pictures with eachcomprising an image produced by the object and each image comprising aplurality of parts corresponding to the plurality of portions; and acomputing apparatus configured to generate motion signals correspondingto the plurality of portions of the object according to changes inpositions and intensity values of the plurality of parts of the images,wherein each picture is obtained by subtracting a picture that is takenwhen the light source is turned off from a picture that is taken whenthe light source is turned on.
 25. The image system of claim 24, whereinthe computing apparatus determines a three-dimensional image of theobject according to the positions and the intensity values of eachimage.
 26. The image system of claim 24, wherein the light source emitsinvisible light and the image sensing device detects the invisiblelight.
 27. The image system of claim 26, further comprising a visiblelight image sensing device configured to generate a visible lightpicture comprising an image of the object, wherein the computingapparatus determines the position and a dimension of one of the parts ofthe image of one picture using the image of the visible light picture.28. The image system of claim 24, wherein the image sensing device is aglobal shutter image sensor.
 29. An image system comprising: a lightsource configured to illuminate an object comprising a plurality ofportions; an image sensing device configured to generate a plurality ofpictures with each comprising an image produced by the object and eachimage comprising a plurality of parts corresponding to the plurality ofportions; and a computing apparatus configured to generate motionsignals corresponding to the plurality of portions of the objectaccording to changes in positions and intensity values of the pluralityof parts of the images, wherein the image sensing device is a globalshutter image sensor, wherein the image sensing device comprises a pixelarray and an automatic exposure control device coupled with the pixelarray, and wherein the automatic exposure control device compares theintensity value representing one of the parts of one of the images witha predetermined intensity range to determine an exposure control value,which is used to determine exposure time of the pixel array.
 30. Animage system comprising: a light source configured to illuminate anobject comprising a plurality of portions; an image sensing deviceconfigured to generate a plurality of pictures with each comprising animage produced by the object and each image comprising a plurality ofparts corresponding to the plurality of portions; and a computingapparatus configured to generate motion signals corresponding to theplurality of portions of the object according to changes in positionsand intensity values of the plurality of parts of the images, whereinthe image sensing device is a global shutter image sensor, and whereinthe computing apparatus compares the intensity value representing one ofthe parts of one of the images with a predetermined intensity range todetermine either the time during which the light source is turned on orthe exposure time of the image sensing device.